This disclosure relates generally to Processes for the conversion of the sulfur compounds to elemental sulfur through different catalytic stages after the reaction furnace of the Claus unit with air or oxygen operation. The first stage or and the second stage of the Claus unit consists of combination of oxygen scavenger catalyst as known as “AM” catalyst which performs as the oxygen scavenger as well as Claus catalyst for any excess oxygen from the reaction furnace burner and the conventional Claus catalyst which is Alumina or combination of alumina and titanium. The third stage will be the direct reduction catalyst consists but no limited to Fe, Ni, Mo, Mn, and Al, for direct conversion of SO2 to sulfur based on the patent reference, U.S. Pat. No. 6,297,189 B1. Finally the fourth stage consists of selective direct oxidation catalyst consists but not limited to Fe, Zn, Mg, Zn, and Cr catalyst for direct conversion of H2S to sulfur without any limitation Using above more selective catalysts are to enhance much higher recovery compare to the conventional Claus up to 99.90% and to produce additional elemental sulfur. The maximum sulfur recovery in the conventional Claus is 93-97% wherein the remaining un recovered sulfur components requires larger tail gas unit. In this new innovation the tail gas feed could be processed in much smaller tail gas treating unit due to much higher recovery. In addition, the caustic scrubber is added after the incineration to meet the zero emission near 100% sulfur conversion.